Final Exam Study Guide - Programming in Perl | CSCI 2230, Exams of Computer Science

Download Final Exam Study Guide - Programming in Perl | CSCI 2230 and more Exams Computer Science in PDF only on Docsity! Name: _______________________________________ RCS ID ____________________________________ Programming in Perl CSCI-2230 Final Exam Rules and Information: 1. TURN OFF ALL CELULAR PHONES AND PAGERS! 2. Make sure you are seated at least one empty seat away from any other student. 3. Write your first name, last name, and RCS ID (not your RIN!) on the top of EACH page 4. Clear your desks/tables of all Calculators, PDAs, and Laptops 5. You may use any book (Camel, Llama, Mouse, or other) and any typed or hand-written notes. 6. You have until 6:00pm EDT to complete this exam. 7. If you have a question, raise your hand. Paul or one of the TAs will come to you. 8. In all of the questions, "write a program", and "write a script" mean to write a *complete* program, from beginning to end (including shebang); "write a piece of code", "write a chunk of code", "write a line" and "write a function" mean just the line(s) of code that satisfy the problem, not an entire program. 9. In any question that requires multiple steps, show all your work to be able to receive partial credit. If no work is given, and the final answer is wrong, you will lose all points for that question. 10. When you have completed the exam bring it to the table in the front of the room 11. Solutions to this exam will be posted on the course website just after 6pm today. 12. When the Exams have been graded, an announcement will be posted to the course website and to the class mailing list informing you where and when you may pick up your exams. 13. Good luck with the remainder of your classes and exams. 14. If you are interested in being an undergraduate Teaching Assistant for this course next semester (assuming it's still offered and Paul is still teaching it…), please email him at lallip@cs.rpi.edu for more information or to apply. Page 1 of 7 Name: _______________________________________ RCS ID ____________________________________ REGULAR EXPRESSIONS (15%) 1) Write a regular expression to match the contents of a C-style comment. Do not match the delimeters or the leading or trailing whitespace. For example: (3pts) /* This is a comment that happens to span multiple lines */ 2) What is the output of this code? (3pts) $string = "aaaab"; if ($string =~ /(a*)a(a|b)/){ print "$1\n"; } 3) Write a regular expression to match the name of any Perl scalar variable, including the $. (Don't concern yourself with matching 'special variables' like $"). Recall that Perl variables must start with a letter or underscore, but the remaining characters may be letters, underscores, or numbers. (3 pts) 4) Why would this not be the best way of ending user input? (3 pts) while ($in !~ /^quit/i){ #do stuff…. print "Enter an input, or the word "quit" to end\n"; } 5) The following code generates a syntax error. Why? How would it be fixed, without changing the look or readability of the code? (3 pts) $pattern =~ m/ #start the regexp (\d*) #search for 0 or more digits, and save them \s+ #at least one whitespace \1 #the same digit pattern ([A-Za-z]) #search and save a single letter /; #end the regular expression Page 2 of 7 Name: _______________________________________ RCS ID ____________________________________ RANDOM BITS OF PERL (20%) 12) Write a program to ask the user for a command. Find out if it is an actual unix command by running the program man <command> (without the brackets). If it is a command, run the command and display the output of the command. If it is not, print a message saying it's not a command. Hint: man returns the message No manual entry for <command>. if it cannot find an entry, and a description of the command if it can. (5 pts) Here are two sample run-throughs of your program (user input is bold): Enter a command: ls output of ls: file1.txt program.pl page.html Enter a command: blargh! Sorry, blargh! is not a command. 13) What is the output of the following piece of code? (show your work for partial credit) (5 pts) @numbers = (1..10); @num2 = map {$_ * 4} @numbers; @num3 = grep {$_ % 3 == 0} @num2; print "The contents of \@num3 are: @num3\n"; 14) What is the output of the following piece of code? (5 pts) $message = "Hello World"; $value = 42; print qq(I was told, "Give him the message: $message".\n); print q("What's the answer"? Well, $value, of course!\n); Page 5 of 7 Name: _______________________________________ RCS ID ____________________________________ 15) Give the contents of each variable after the following chunk of code (show your work for partial credit) (5pts): $a = 10; $b = 40; $c = 15; $x = -5; $y = -10; $z = 0; ($a, $b) = ($b, $a); ($y, $c, $z) = ($b*2, $x); ($x) = ($a, $b); $c = ($y, $x); CGI (25%) 16) Why would this code not work properly? (5 pts) 17) Assume some HTML form contains two submit buttons. One is named Submit1 (and labeled "Go!"), the other is named Submit2 (and labeled "Now!"). Write a piece of a CGI script to determine which button was pressed, and output a message indicating which was pressed. (You do not have to write the code to actually generate the form or the buttons) (5 pts) Page 6 of 7 #!/usr/local/bin/perl –w use CGI qw(standard); print <<HTML; <html><head><title> My Title </title></head> <body> la la la. Foo bar. B'bye! </body></html> HTML Name: _______________________________________ RCS ID ____________________________________ 18) The contents of the following form are displayed below. If the user has filled out the form as shown, and dump.cgi simply prints the header, starting HTML, the return value of Dump(), and ending HTML, show the output of dump.cgi: (5 pts) <form method="post" action="dump.cgi"> <input type="text" name="message"><br> <input type="checkbox" name="choice" value="Lally">Lally<br> <input type="checkbox" name="choice" value="AmosEaton">Amos Eaton<br> <input type="checkbox" name="choice" value="DCC">DCC<br> <input type="submit" name="Submit" value="GoThere"> 19) Write a CGI script to display a form containing a textbox, two radio buttons, and a submit button. The radio buttons are marked "RPI" and "CS Dept". The user of your script enters his RCS user Id in the text box, and chooses one of the two radios. When the user presses the submit button, your script displays a page saying which radio was selected, and create an HTML link to that user's webpage, on either the RPI or CS Dept system. For example, if I enter my user id and select CS Dept, your script generates: You have chosen the CS Dept. Your home page is <a href="http://www.cs.rpi.edu/~lallip">here<a> If I select RPI, the link instead goes to www.rpi.edu/~lallip If the user does not enter a UserId, you should display an error message and nothing else. (10 pts) Page 7 of 7 Why not change the world x x Lally DCC Amos Eaton GoThere